2026 Water Cycle White Paper | Chapter 12026 Water Cycle White Paper: Promoting Watershed Cooperation

Article 12 of the Basic Act on the Water Cycle (Act No. 16 of 2014) requires the government to submit an annual report on water cycle measures to the Diet. This volume reports on measures taken in fiscal 2025.

The chapter is titled “Chapter 1: Promoting Watershed Cooperation and Related Measures — A Framework for Comprehensive and Integrated Watershed Management.” The special feature explains that the water cycle spreads across the land from upstream to downstream and also has a three-dimensional reach connecting surface water and groundwater. It presents an approach that considers the entire watershed, rather than only the locations where problems occur.

Examples of challenges include securing water quantity and quality, conserving and replenishing water sources, conserving and using groundwater, and protecting ecosystems. In recent years, efforts have also expanded to address water disasters intensified and made more frequent by climate change, and to promote regional development by using the water cycle as a local resource.

Integrated watershed water management brings together flood management, water use, and watershed environment conservation. It aims to achieve outcomes such as minimizing damage from water disasters and maximizing the benefits of water.

In Toba City, support was provided for efforts contributing to improvements in the water cycle from forests through rivers to coastal waters and the recovery of marine resources. This included surveying and assessing candidate sites for forestry operations and advising on methods for measuring and analyzing water cycle data.

The Basic Plan on the Water Cycle, approved by the Cabinet on August 30, 2024, clarified the concept of “watershed management,” which puts into practice the principle of comprehensive and integrated watershed management. A Watershed Water Cycle Council made up of relevant stakeholders is established for each watershed, and a Watershed Water Cycle Plan setting out basic policies and other matters is drawn up. Measures are then advanced based on the plan. Rather than having one manager oversee the entire watershed, this framework enables public institutions, experts, businesses, organizations, and residents to work together across forests, rivers, farmland, cities, lakes and marshes, coastal areas, groundwater basins, and other settings.

Since fiscal 2016, the government has published a nationwide list of watershed water cycle plans. The plans published in fiscal 2025 were Shizuoka Prefecture’s “Ota River Basin Watershed Water Cycle Plan,” Sendai City’s “Hirose River Creation Plan,” and Hachioji City’s “Hachioji City Water Cycle Plan”; the latter two revised existing plans. The government promotes the development and strengthening of plans in areas where groundwater conservation is important and in areas pursuing regional development that makes use of water, among others.

In June 2025, a subcommittee of the National Land Council and a working group of the Council for Social Infrastructure Development issued a report titled “On the Future of Integrated Watershed Water Management.” Based on the report, the government will progressively develop collaborative initiatives involving stakeholders throughout each watershed, tailored to its characteristics.

The “Watershed Management Guide” sets out practical procedures for establishing councils, preparing plans, securing funding, and other tasks. First developed in July 2018 and revised in January 2024, it was revised for a second time in March 2026 to reflect changes to the Basic Plan on the Water Cycle and efforts based on its road map. The revised guide will be publicized, and advisers and other support will be provided to local governments and others working to develop plans.

Since fiscal 2020, water cycle advisers have been dispatched to local governments and other entities upon request to provide technical advice and recommendations. In fiscal 2025, seven local governments received support. Examples include Shizuoka City’s water resources and groundwater use; Aichi Prefecture’s paddy field dams; groundwater assessment in Iga City; a groundwater impact survey and water quality testing system for the Chusan Wide Area Administrative Association; high school student participation in Komoro City; and revision of Matsuyama City’s long-term water supply and demand plan.